CS spray was used by officers, but it is not yet known if it contributed to the 36-year-old's death.

The Police Ombudsman's Office has used security camera footage to find out Mr McMahon's movements.

The Short Strand man died after being arrested at around 5am following an altercation close to the Grand Opera House on Great Victoria Street.

Investigators have renewed their appeal for anyone who saw what happened during that incident to contact them.

They have also appealed for information from anyone who may have seen Mr McMahon at a number of locations in the city centre between 2am and 5am.

They include Patterson's Place, off Donegall Square East, where he left a nearby nightclub shortly after 2am. At that stage he was wearing a turquoise colour Firetrap T-shirt, black jeans with a yellow belt, and black trainers.

He then moved to the Howard Street area, behind the City Hall, and was there between approximately 2.30am and 3am, by which stage he was partially undressed.

Investigators have obtained evidence that he then moved to the Friendly Street area of The Markets, and was there between roughly 3.15am and 4.30am, before making his way to Great Victoria Street via Hamilton Street.

He was also seen in Amelia Street and Brunswick Street, close to Victoria Street.

Senior investigating officer Paul Murphy said: "We have obtained a significant amount of CCTV footage, but if anyone has any other information or material which may assist our enquiries, we would be grateful if they could contact us."